The realization of exciton-based quantum memories is fundamentally hindered by the trade-off between optical accessibility in bright states and long coherence lifetimes in dark states. While interlayer excitons offer promising lifetimes, their optical selection rules are typically locked by crystal symmetry, preventing dynamic switching via external fields. Here, we demonstrate a mechanism to deterministically toggle interlayer excitons between bright and dark states by leveraging sliding ferroelectricity within the framework of ferrovalley physics. By establishing a general symmetry criterion, we identify bilayer GeS${}_2$ as an ideal platform where interlayer sliding not only reverses the out-of-plane dipole but also rotates the optical principal axis by 90${}^{\circ }$. Our calculations reveal that this structural reconfiguration switches the excitonic state at a specific valley from bright to dark for a fixed linear polarization, while simultaneously locking the excitation to a single valley. This establishes a non-volatile and electrically reconfigurable coupling between ferroelectricity and excitonic optical activity, in which the bistable stacked structures encode different bright and dark exciton channels. These findings bridge ferroelectric control with exciton quantum optics, suggesting a viable path towards ultra-low-power optoelectronic memories and reconfigurable valleytronic routers.